Install-Exchange15 VS Set-OutlookSignatures

I have used a script in the past for upgrades and plan to use it again for an Exchange 2013 to 2019 migration. This is the script: https://github.com/michelderooij/Install-Exchange15

Export the database and certificates. Then create new machine with the same parameters as the old one (Name,Windows/Exchange Version) and do an exchange recovery. You can also use this Script for easy automation: https://github.com/michelderooij/Install-Exchange15 After Recovery import database and certificates. Then you should be done.

Set-OutlookSignatures might be what your are looking for: https://github.com/Set-OutlookSignatures/Set-OutlookSignatures

In my experience, the easiest way is to use a software for central management of signatures, such as Set-OutlookSignatures. Set-OutlookSignatures not only allows you to use Word or HTML templates, it also includes features to ensure maximum signature compatibility across different mail clients. There is also a lot of other features that come in handy, such as support for roaming signatures.

I've heard positive things from this project: https://github.com/GruberMarkus/Set-OutlookSignatures

there is 3rd party tools out there (for example CodeTwo), there is also a very good powershell option https://github.com/GruberMarkus/Set-OutlookSignatures

A service like code two is most of the time worth the money, but if you really want to go the code way have a look here: https://github.com/GruberMarkus/Set-OutlookSignatures

A redditor posted his solution some time ago and we use it at work. It's a PowerShell script that gets the data from AD or AAD and creates signatures based on a template. Check https://github.com/GruberMarkus/Set-OutlookSignatures (manually typed link, so excuse any errors).